The Clinical Coordinating Center for the Clinical Trial and Observational Study of the Women's Health Initiative will take the lead in developing the study Protocol and Manual of Operating Procedures in cooperation with the Vanguard Clinical Centers and the NIH. It will coordinate study activities needed to successfully implement the Protocol, including study data collection, and will be responsible for central data management, analysis, and reporting. In addition, it will be responsible for the central laboratories, central storage facility, and the drug distribution center.